I apologize to those that don't like my tone.
just be aware your tone is turning people off from helping you and continues in your latest post.
but as M$ drove all competitors out of the desktop and mini markets
competitors exist, some open source. OK not as big as MS in some respects but they are out there all the same. Android, Apple to name two, then there is linux, oracle and the like. Not everyone uses windows devices, but many business do. If my target audience was the general public, I would be looking to develop under android and/or apple - there are a lot more general public customers than business customers.

With regards two way syncing, I explained in a previous thread of yours what is required - multiple queries plus coding to handle clashes. My concern with composite primary keys, although usable and does the job of uniquely identifying a record means that all child records need to carry the composite key as a FK as well.

I mentioned in a previous thread about using a random autonumber which provides some element of protection from clashes being generated in different systems returning the same number. Something else for you to consider